Science (English Medium) Class 12 - CBSE Question Bank Solutions for Biology

State the importance of elution in this process.

Given below is the restriction site of a restriction endonuclease Pst-I and the cleavage sites on a DNA molecule.

\[\ce{5' C - T - G - C - A \overset{\downarrow}{-}{G 3'}}\]

\[\ce{3' G\underset{\uparrow}{-} A - C - G - T - C 5'}\]

Choose the option that gives the correct resultant fragments by the action of the enzyme Pst-I.

Given below are the list of the commercially important products and their source organisms. Select the option that gives the correct matches. 

Important attributes belonging to a population but not to an individual are:

1. Birth rate and death rate
2. Male and female
3. Birth and death
4. Sex-ratio

Select the correct option from the given options:

'EcoRI' has played a very significant role in rDNA technology.

1. Explain the convention for naming EcoRI.
2. Write the recognition site and the cleavage sites of this restriction endonuclease.

What are the protruding and hanging stretches of DNA produced by these restriction enzymes called? Describe their role in the formation of rDNA.

State the principle involved in separation of DNA fragments using gel electrophoresis.

How are DNA fragments visualised once they are separated by gel electrophoresis?

Identify the activity of endonuclease and exonuclease in the given image.

Name the selectable markers in the cloning vector pBR322. Mention the role they play.

Explain the different steps involved during primary treatment phase of sewage.

Explain the process of secondary treatment given to the primary effluent up to the point it shows significant change in the level of biological oxygen demand (BOD) it.

Explain co-evolution with reference to parasites and their hosts.

State how has Agrobacterium tumifaciens been made a useful cloning vector to transfer DNA to plant cells.

What is primary productivity?

Write the equation that helps in deriving the net primary productivity of an ecosystem.

Why a transgenic animals so called?

Explain the role of transgenic animals in (i) Vaccine safety and (ii) Biological products with the help of an example each.

Draw a schematic sketch of pBR 322 plasmid and label the following in it:

(a) Any two restriction sites.

(b) Ori and rop genes.

(c) An antibiotic resistant gene.

Explain the function of “anaerobic sludge digester” in a sewage treatment plant.